JPH07108661A - Easy adhesive polyester film and production thereof - Google Patents

Abstract

PURPOSE:To obtain a polyester film showing an excellent adhesiveness to the active energy curable paint/ink applied on the polyester film. CONSTITUTION:A primer layer of copolyester with a glass transition temp. of 25 deg.C or higher having an unsaturated double bond in its terminal or side chain is provided on at least one surface of a polyester film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-adhesive polyester film and a method for producing the same, and more particularly to ultraviolet curable paints and inks, electron beam (EB) curable paints and inks, especially EB curable magnetic paints. The present invention relates to an easily-adhesive polyester film exhibiting excellent adhesiveness to a film and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Thermoplastic polyesters such as polyethylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-
Naphthalene dicarboxylate or copolymers thereof, or blends of these with a small proportion of other resins are melt-extruded, biaxially stretched, and heat-fixed. Polyester film has mechanical strength, heat resistance, and chemical resistance. Etc., and is used in various industrial fields. However, since its surface is highly oriented and crystallized, there is a problem that it is poor in acceptability of paints, adhesives, inks and the like.

Therefore, as a method for improving this adhesiveness, physical treatment such as corona treatment, ultraviolet treatment, plasma treatment, EB treatment or flame treatment, or chemical treatment such as alkaline aqueous solution, amine aqueous solution, trichloroacetic acid phenols or the like is used. Processing is known. However, these methods have practical disadvantages such as deterioration of adhesive strength with time and contamination of working environment due to volatilization of chemicals.

As another means, a method is known in which a primer layer is formed by coating an easily adhesive coating on the film surface by a process other than the usual polyester film forming process. However, in this method, an organic solvent is usually used as the solvent for the coating agent, and since it is hard to say that the coating atmosphere is sufficiently clean, the occurrence of surface defects of processed products due to the adhesion of dust, or the environment caused by the organic solvent. There are safety and hygiene problems such as deterioration.

Therefore, if this primer treatment is carried out in a polyester film forming process using a water-based coating agent, dust will not adhere in a clean environment, and the water-based solvent may cause an explosion or deterioration of the environment. Without film performance, economics,
It is advantageous in terms of safety.

By the way, active energy ray curable paint
Ink is advantageous in terms of cost because it overcomes the drawbacks of thermosetting paints and inks such as thermal deformation obstacles and lengthening of the heating oven due to the length of curing time, and the reaction can be completed in a short time at cool temperature. Is. In particular, the EB treatment has many advantages such as a high reaction rate due to its high energy and a simultaneous double-sided curing treatment of a thin layer material utilizing the osmotic force.

However, the curing by the active energy ray has a large curing shrinkage ratio of the paint / ink due to the addition polymerization reaction occurring in a short time, so that the stress is concentrated on the boundary surface between the primer layer and the paint / ink, It has the drawback of reducing the adhesion between the two.

[0008]

DISCLOSURE OF THE INVENTION An object of the present invention is to improve the decrease in adhesive strength due to stress concentration at the interface generated when an active energy ray-curable coating material / ink coated on a polyester film is cured, An object of the present invention is to provide an easily-adhesive polyester film having improved adhesiveness with the coating material / ink and a method for producing the same.

[0009]

The object of the present invention is to:
According to the invention: An easy-adhesive polyester film having a glass transition temperature of 25 ° C. or higher and a primer layer of a copolyester having an unsaturated double bond at an end or a side chain on at least one side of the polyester film,
And 2. An aqueous primer solution containing a copolyester having a glass transition temperature of 25 ° C. or more and an unsaturated double bond at an end or a side chain is applied to at least one surface of a polyester film in which oriented crystallization has not been completed, and then dried. ,
This is achieved by a method for producing an easily-adhesive polyester film, which comprises stretching and heat-treating to complete the oriented crystallization of the film.

In the present invention, the polyester constituting the polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6.
Examples thereof include naphthalene dicarboxylate, and copolymers of these or blends of these with small proportions of other resins are also included.

The polyester of the present invention may contain an agent for improving film properties, such as a lubricant, an antistatic agent, a colorant, a flame retardant, a light-shielding agent, a stabilizer and an ultraviolet absorber. The lubricant may be either internally precipitated particles or externally added particles, or may be a combination of two or more kinds. Examples of externally added particles include silica, kaolin, calcium carbonate, calcium phosphate,
Titanium oxide and the like can be mentioned, and examples of the internally deposited particles include those precipitated during the production of polyester with a combination of an alkali (earth) metal compound, a phosphorus compound and the like.

The polyester in the present invention is known per se and can be produced by a known method. Intrinsic viscosity of polyester (o-chlorophenol, 35
C) is preferably 0.45 to 0.9.

In the present invention, the polyester film may be produced by the following method. That is, first, polyester is melt-extruded by a conventional method and cooled to solidify to obtain an amorphous unstretched film. Then, this unstretched film is first stretched in the machine direction and then stretched in the transverse direction. These stretchings are performed by running the film. As the stretching means in the machine direction and the transverse direction, known means can be used. For example,
The longitudinal stretching (longitudinal stretching) is performed by heating the unstretched film with a heating roll group and utilizing the peripheral speed difference between the low speed roll and the high speed roll. At that time, it is preferable to provide an infrared heater between the low speed roll and the high speed roll to heat the film to the stretching temperature, or the low speed roll may heat the film to the stretching temperature. This stretching in the machine direction is usually performed at a magnification of 2.5 to 4.5 times. The transverse stretching (transverse stretching) is performed using a tenter type stretching heat treatment device. This transverse stretching is usually performed at a magnification of 2.5 to 4.5 times. Then 150-2
Heat treatment at a temperature of 40 ° C. to improve oriented crystallization.

In addition to the sequential biaxial stretching method, the polyester film may be stretched by simultaneous biaxial stretching method or multi-stage stretching method (length-width-length, length-width-length-width, length-length-width, length). -side-
Horizontal, etc.) can also be used.

In the present invention, the copolyester having an unsaturated double bond at the terminal or side chain constituting the primer layer is mainly synthesized from a polybasic acid or its ester-forming derivative and a polyol or its ester-forming derivative. And a substantially linear polyester having an unsaturated double bond at the terminal or side chain of the molecule.

The polybasic acid component of this polyester includes terephthalic acid, isophthalic acid, phthalic acid, p, p '.
-Diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phenylindanedicarboxylic acid, phenylquinoxalinedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, dimer acid, etc. can do.
Two or more of these components can be used.

As the polyol component, ethylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylol. Propionic acid, glycerin, trimethylolpropane,
Examples thereof include poly (ethylene oxide) glycol, poly (tetramethylene oxide) glycol and the following bisphenol A derivatives. These can use 2 or more types.

[0018]

[Chemical 1]

(Where R is H or CH ₃ , and m and n
Is an integer, and m + n = 2 to 10)

The above-mentioned copolyester forms an aqueous solution by copolymerizing a hydrophilic group-containing compound such as an organic sulfonate, a carboxylate, diethylene glycol, polyethylene glycol, polytetramethylene glycol, etc. in the molecule. It is advantageous and preferable.

To introduce a sulfonate group into the copolymerized polyester molecule, for example, 5-Nasulfoisophthalic acid, 5-ammoniumsulfoisophthalic acid, 4-Nasulfoisophthalic acid, 4-methylammoniumsulfoisophthalic acid, 2-Na sulfoterephthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, 2-K sulfoisophthalic acid, Na sulfosuccinic acid, or other sulfonic acid alkali metal salt-based compound or sulfonic acid amine salt-based compound can be used. preferable. The polyvalent carboxylic acid or polyhydric alcohol having a sulfonate group is 0.5 to 20 mol% in the total polyvalent carboxylic acid component or polyhydric alcohol component, and further 1 to
It preferably accounts for 18 mol%.

In order to introduce a carboxylic acid group into the copolymerized polyester molecule, for example, trimellitic acid anhydride, trimellitic acid, pyromellitic acid anhydride, pyromellitic acid, trimesic acid, cyclobutane tetracarboxylic acid,
A compound such as dimethylolpropionic acid can be used. The carboxylic acid salt can be obtained by neutralizing the carboxylic acid with an amino compound, ammonia, an alkali metal or the like.

When introducing the hydrophilic group-containing compound into the copolyester molecule, various known methods can be adopted. The case of introducing a carboxylate or organic sulfonate group will be further described. For example, a method for synthesizing a polyester using a compound having a carboxylate or organic sulfonate group in the molecule as a starting material, After synthesizing a polyester using a compound having three or more carboxylic acid groups therein as one component of a starting material, the free carboxyl group in the polyester is converted to ammonia,
There are methods such as a method of neutralizing the medium with an amine or an alkali metal compound. The method will be further described. For example, trimellitic anhydride was used as one component of the polyester raw material to prepare a polymer having a free carboxyl group in the side chain, and after the reaction was completed, ammonia water was added to neutralize the aqueous polyester. Can be built. The copolymerized polyester is preferably produced by a melt polymerization method.

The copolymerized polyester can be produced by a conventional polyester production technique. For example, terephthalic acid or its ester-forming derivative, isophthalic acid or its ester-forming derivative, and 5-sodium sulfoisophthalic acid or its ester-forming derivative are reacted with ethylene glycol and an ethylene oxide adduct of bisphenol A to form a monomer. Alternatively, it can be produced by a method of forming an oligomer and then polycondensing it under vacuum to obtain a polyester having a predetermined intrinsic viscosity. At this time, a catalyst that accelerates the reaction, such as an esterification or transesterification catalyst or a polycondensation catalyst, can be used, and various additives such as a stabilizer can also be added.

In order to introduce an unsaturated double bond into the terminal or side chain of the polyester, for example, an unsaturated compound having reactivity with a carboxyl group or a hydroxyl group at the terminal or side chain of the polyester, For example, there is a method of reacting 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, glycidyl allyl ether and the like. Such a reaction can be performed in a solid phase, a solution, or an emulsion.

The intrinsic viscosity of the copolyester in the present invention is preferably 0.2 to 0.8. Here, the intrinsic viscosity is a value measured at 35 ° C. using o-chlorophenol.

In the present invention, the unsaturated double bond based on the copolyester in the primer layer chemically reacts with the curing agent in the active energy ray-curable coating material / ink on the primer layer when it is cured. The adhesiveness of the paint / ink is improved. The amount of the unsaturated double bond is (0.3 to 30) × 10 ⁻⁴ equivalent / g, more preferably (0.5 to 25) × 10 ⁻⁴ equivalent / g, and particularly (1 to 20) 10 ^−4. It is preferably equivalent weight / g.
When the amount of this unsaturated double bond is less than 0.3 × 10 ⁻⁴ equivalent / g, the adhesiveness with the active energy ray-curable coating material / ink is deteriorated, while when it exceeds 30 × 10 ⁻⁴ equivalent / g, the polyester is Adhesion to the film is reduced, which is not preferable.

The active energy rays referred to in the present invention are ultraviolet rays, X-rays, electron beams and radiation. Considering the price of the device, management, and the influence on the human body, ultraviolet rays and electron beams are practical.

The aqueous primer solution of the present invention preferably contains a wetting agent in order to improve the wettability to the polyester film. The wetting agent is preferably a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant, for example, a polyethylene oxide / polypropylene oxide block copolymer, polyoxyethylene alkylphenyl ether, polyoxy. Ethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkane sulfonate, alkyl sulfur salt, alkylbenzene sulfonate, alkyl sulfonate, alkyl diphenyl ether disulfonate, alkyl sulfosuccinate, quaternary ammonium salt Examples thereof include chloride salt and alkylamine hydrochloric acid. Among these, nonionic surfactants are more preferable in terms of liquid stability.
The amount of the wetting agent is preferably 2 to 30% by weight, and more preferably 3 to 20% by weight based on the total solid content of the primer.

Further, other additives such as an ultraviolet absorber, a pigment, an organic filler, an inorganic filler, a lubricant, an antiblocking agent, and a cross-linking agent such as melamine, epoxy, aziridine, etc. may be added within a range in which the effects of the present invention are not lost. Can be mixed.

The solid content concentration of the aqueous coating solution is usually 30% by weight.
It is below, and more preferably 10% by weight or less. The coating amount is preferably 0.5 to ²⁰ g, and more preferably 1 to 10 g per 1 m ² of the running film.

As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method and a curtain coating method may be applied alone or in combination. The aqueous coating liquid may contain a small amount of an organic solvent for the purpose of assisting stability of the coating liquid or coatability of the coating liquid.

After the application of the aqueous primer solution, the aqueous primer layer is formed by a drying treatment. When the oriented crystallization of the polyester film is not completed, for example, a longitudinally stretched polyester coated with the aqueous primer solution is used. The film is dried and introduced into steps such as transverse stretching and heat setting. The longitudinally stretched polyester film coated with the aqueous primer solution is introduced into, for example, a stenter and laterally stretched and heat set. During this time, the coating solution is dried to form a continuous film on the film. Drying may be performed before or during transverse stretching.

The polyester film coated with the aqueous primer layer thus obtained has good adhesiveness to the active energy ray-curable coating material / ink, and particularly, a recording medium using a UV ink or an electron beam-curable magnetic coating material (eg, a recording medium). , Video tapes, audio tapes, computer tapes, floppy disks, etc.) are useful as an easily-adhesive polyester film.

[0035]

EXAMPLES The present invention will be further described below with reference to examples. In addition, "part" in an example means a "weight part." Each characteristic of the film was measured by the following method.

1. Adhesiveness The evaluation coating material was applied to the primer-coated polyester film with a Meyer bar so that the thickness after drying was about 2 μm, and dried at 100 ° C. for 3 minutes. This coating film was irradiated with an electron beam accelerator in an N ₂ atmosphere at an acceleration voltage of 150 KV for 10 Mr.
The electron beam of ad was irradiated. The cured magnetic layer was abraded by a RCA abrasion tester under a load of 50 g for 1.3 seconds each time, and the number of times the base surface was rubbed was measured.

[Magnetic paint for evaluation] Polyurethane resin in terms of solid content 50 parts Unsaturated polyester resin 30 parts Polyethylene glycol dimethacrylate 18 parts Dispersant 2 parts γ-Fe ₂ O ₃ 500 parts Mixture of methyl ethyl ketone / toluene / cyclohexanone Dissolve in solvent, make 40% solution and use sand grinder to do 2
Magnetic dispersion was obtained by time dispersion.

2. Blocking resistance The treated surface and non-treated surface of two films are superposed, and a pressure of 6 kg / cm ² is applied to this for 17 hours in an atmosphere of 50 ° C. × 70% RH and then peeled off, and the peeling force is evaluated. (G per 5 cm width).

Examples 1 to 3 Polyethylene terephthalate (containing a lubricant) having an intrinsic viscosity of 0.65 at 170 ° C.
280 on a rotating cooling drum maintained at 20 ° C after drying for an hour
After melt-extruding at a temperature of 50 ° C. to obtain an unstretched film having a thickness of 150 μm, and then longitudinally stretching 3.8 times by an infrared heater method,
90 parts of the coating material 1 (Example 1), coating material 2 (Example 2) or coating material 3 (Example 3) below contained 4 wt% of a nonionic surfactant (polyoxyethylene alkylphenyl ether HL).
An aqueous primer solution (4 wt%) prepared by mixing 10 parts of an aqueous solution of B = 12.8) was applied to one side of the longitudinally stretched film by a kiss coating method at a rate of Wet 8 g / m ² . Continue 1
Stretched laterally 3.9 times at 05 ° C, then 6 at 215 ° C.
Heat setting was performed for 2 seconds. The film thickness at this time is 75 μm
And the thickness of the final primer layer was 0.08 μm. The characteristics of this film are shown in Table 1.

[Coating 1] Terephthalic acid 70 as an acid component
Mol%, isophthalic acid 17 mol%, trimellitic acid 3 mol% and 5-Na sulfoisophthalic acid 10 mol%, and ethylene glycol 95 mol% as a glycol component.
And a polyester using 5 mol% of diethylene glycol was dissolved in tetrahydrofuran (THF), glycidyl methacrylate was added thereto and reacted at 60 ° C., and a copolyester having an unsaturated double bond in a side chain (Tg: 38 C., a solution having an unsaturated double bond amount of 1.3 × 10 ⁻⁴ equivalent / g) was obtained. After adding water to this, THF was desolvated by heating distillation to obtain an emulsion liquid having a solid content of 4%.

[Coating 2] Glycidyl acrylate was used in place of glycidyl methacrylate in Coating 1 to obtain an emulsion liquid having a solid content of 4%. The Tg of the copolyester is 38 ° C. and the amount of unsaturated double bonds is 1.3 × 10.
^-4 equivalent / g.

[Coating agent 3] 80 terephthalic acid as an acid component
Mol%, isophthalic acid 15 mol% and trimellitic acid 5
Polyol using 95 mol% of ethylene glycol as a glycol component and 5 mol% of diethylene glycol as a glycol component was dissolved in THF, and then 40% of the carboxyl groups of the polyester was reacted with glycidyl methacrylate, and then NaOH water of pH 9 was used. Was added to neutralize residual carboxyl groups. The Tg of the obtained copolyester was 50 ° C., and the amount of unsaturated double bonds was 1 × 10 ⁻⁴ equivalent / g. Then, this solution is heated and distilled to obtain a solid content of 4%.
An emulsion liquid of was obtained.

Comparative Example 1 A biaxially oriented film was obtained in the same manner as in Example 1 except that the aqueous primer solution was not applied. The characteristics of this film are shown in Table 1.

[0044]

[Table 1]

As is apparent from Table 1, the polyester film of the present invention has excellent adhesiveness to electron beam curable magnetic paints and inks.

[0046]

INDUSTRIAL APPLICABILITY According to the present invention, various active energy ray-curable coating materials / inks, such as UV-curable hard coat coating materials, UV inks, electron beam curing coating materials / inks, particularly electron beam curing type, which are applied to polyester films, can be obtained. It is possible to provide an easily-adhesive polyester film having a primer layer exhibiting excellent adhesiveness to a magnetic paint and a method for producing the same.

Claims (2)

[Claims] 1. An easy-adhesion characterized in that a primer layer of a copolyester having a glass transition temperature of 25 ° C. or higher and an unsaturated double bond at an end or a side chain is provided on at least one side of a polyester film. Polyester film. 2. A glass transition temperature of 25 ° C. on at least one side of a polyester film which has not been oriented and crystallized.
The above is characterized in that the aqueous primer solution containing the copolymerized polyester having an unsaturated double bond at the terminal or side chain is applied, and then dried, stretched and heat-treated to complete the oriented crystallization of the film. A method for producing an easily-adhesive polyester film.